The invention relates to a control method and a respective module for occupant protection systems, especially in motor vehicles, with a central unit and a plurality of modules interconnected by a bus system.
Such a control method is disclosed especially in the non-prepublished German Patent Application DE 196 46 387, but is also fundamentally disclosed, for example, in an article by Zimmermann; xe2x80x9cCAN-Serial Data Transmission for Real Time Demandxe2x80x9d, in: Elektronik 5/1991, pages 76-78.
It has turned out to be a disadvantage that, before a rated information is allocated, the modules can contain a quasi undefined random information in the cells or memory locations required for storing information in a module. If an actual information is received by such a module that has not yet been provided with a rated information, then it can happen that the comparison between the actual information and the random information satisfies the relationship predetermined for triggering, and triggering occurs. Also, disturbances caused by electromagnetic fields (EMV) or electrostatic charging (ESD) can generate signals at the input of the module that correspond quasi to such an actual information and lead to a triggering and deployment for example of a protection device such as an airbag. In addition to substantial costs for the repair and/or replacement of a module that has been falsely triggered, personnel responsible for assembling such modules may also possibly be exposed to untenable safety risks, especially from pyrotechnically triggered modules (airbags, belt tensioners, etc.).
Furthermore, German Patent Publication 43 15 494 C1 discloses an arrangement and a method for programming at least one motor vehicle control device in which at least one of the control devices is continuously supplied with power, even when the vehicle is not operating, and has a memory for vehicle configuration data. The at least one device deletes its memory when the device is removed from the vehicle, but nevertheless, has a resistant programmed program by means of which it can determine an electronic xe2x80x9cnon-programmed tagxe2x80x9d or as such can determine that the memory is empty. The tag or empty fact can be used as a criterion for independently calling up the required vehicle configuration data from a central control unit. Even such a method cannot ensure that interference signals on the bus system will not lead to a premature triggering of an occupant protection device.
Therefore it is an object of the invention to provide a control method and a module by means of which the described disadvantages of the prior art, such as the premature triggering of a safety device, are avoided.
This object has been achieved by the present method for preventing a premature, accidental triggering of at least one module (3) including at least one memory location in an occupant protection system for a motor vehicle, said method comprising the following steps:
a) first entering a blocking information into said at least one memory location for preventing triggering of said at least one module until said occupant protection system has been installed in said motor vehicle,
b) installing said occupant protection system in said motor vehicle, and
c) second entering a rated information into said at least one memory location thereby cancelling said blocking information, whereby the same memory location is used first for temporarily storing said blocking information and then for storing said rated information after said installation is completed.
Due to the entry of the blocking information, premature or accidental triggering of modules not yet provided with a rated information is effectively prevented. The use of the same memory location for blocking information and for rated information makes possible a particularly simple activation and a low requirement for components.
It is particularly advantageous if the module or modules to be installed in a safety system is automatically set by the blocking information during manufacturing of the module or modules. All modules thus contain the blocking information during transport and during assembly. The modules are thus initially activated only after installation in the passenger protections system.